Improperly secured furniture, especially on the upper floors of high-rise buildings under long-period ground motion, can become dangerous objects for human life. Many tumbled furniture such as chairs and desks in schools could become fatal obstacles that obstruct children from evacuating. In this research, an effective numerical code to analyze the motion behaviors of furniture subjected to seismic excitations was developed. The numerical code was developed based upon the adaptively shifted integration (ASI) Gauss technique, which is a finite element scheme that provides higher computational efficiency than the conventional code. The frictional contact between objects was fully considered by employing a sophisticated penalty method. Some excitation tests of furniture on a shake-table were carried out, where steel cabinets were excited by seismic waves and the displacement data were recorded by a motion capture system. The numerical results were validated by comparing with the shake-table test results.